Gilbert is not an honest, reliable son; he looks after Arnie, but does not fulfil his duties as a son. He is constantly making fun or sarcastic comments about his mother. For example, Tucker, one of his best friends, is trying to have a pleasant, well mannered conversation with Gilbert, but the subject of Gilbert's mother comes up Tucker says "How's Momma?" Gilbert says "She's fat. . . Tucker she's a whale!"
His smart comments are plentiful and never ending. He is decent around Momma as he never says anything to her face. This is Gilbert's way of dealing with the fact that his mother is overweight. These comments make the watcher cringe and feel uneasy about the way he is treating the issue, he sounds exceedingly harsh and unnecessary. This is important as it shows us that Gilbert is uneasy about the way everyone sees his mother and eventually he gets over it and does the amicable thing by letting his mother go without making a joke or scene of her.
He also treats his Momma, with love and compassion. He never does or says anything to her face that would emphasize the enormity of her weight problem. One example of this is when Tucker is fixing the floor boards because they can't hold the weight of Momma and need reinforcement, Tucker shouts "I'll need some more planks these aren't going to hold up this weight" as soon as Gilbert hears Momma he tries to quieten Tucker down so Momma isn't offended. When watching this the watchers think this is a kind and admirable thing to do. This makes us